In recent years, professional learning has been recognised as a key feature of teacher education and increasingly as a career-long endeavour. To explore the complexity of the professional learning process, this chapter engages in a reflective critique of the non-linear and 'messy' trajectory of the professional learning efforts of the Developmental Physical Education Group's (DPEG) at the University of Edinburgh. It discusses the DPEG's theoretical shift towards complexity thinking, how this impacted on the group's own professional learning and the way it now approaches the professional learning of students and teachers in a more transformative manner. Initially, ideas from ecological theory, dynamical systems, social constructivism and situated learning all proved helpful in making better sense of the group's efforts to reconceptualise primary physical education, although these ideas also led to some disconnect as the different perspectives influenced different elements of the group's work in curriculum, pedagogy and professional learning.